Validation of a new risk stratification system-based management for methicillin-resistant Staphylococcus aureus bacteraemia: analysis of a multicentre prospective study.

PURPOSE: Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteraemia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the heterogeneity of SAB and encouraging targeted diagnostics. Recently, a new risk stratification system for SAB metastatic infection, involving stepwise approaches to diagnosis and treatment, has been suggested. We assessed its applicability in methicillin-resistant SAB (MRSAB) patients. METHODS: We retrospectively analysed data of a 3-year multicentre, prospective cohort of hospitalised patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes. RESULTS: Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection. No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 19.6% in the high-risk groups (P < 0.001). After an in-depth diagnostic work-up, patients were finally diagnosed as 'without metastatic infection (6.3%)', 'with metastatic infection (17.4%)', and 'uncertain for metastatic infection (76.3%)'. 30-day mortality increased as the severity of diagnosis shifted from 'without metastatic infection' to 'uncertain for metastatic infection' and 'with metastatic infection' (P = 0.09). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteraemia score ≥ 4, and persistent bacteraemia. CONCLUSIONS: The new risk stratification system shows promise in predicting metastatic complications and guiding work-up and management of MRSAB. However, reducing the number of cases labelled as 'high-risk' and 'uncertain for metastatic infection' remains an area for improvement.

Diagnostic Usefulness of Varicella Zoster Virus-Specific Immunoglobulin (Ig) A and IgG in Patients With Herpes Zoster.

BACKGROUND: Whether varicella zoster virus (VZV) antibody titer could discriminate patients with herpes zoster (HZ) from healthy controls (HCs) is unclear. We evaluated the diagnostic usefulness of VZV-specific immunoglobulin A (IgA) and immunoglobulin G (IgG) antibodies in patients with confirmed HZ. METHODS: Study subjects comprised patients with confirmed HZ by salivary VZV DNA positivity and control age- and sex-matched HCs. Saliva was collected and concurrent blood samples were obtained on the first visit day (acute phase) and after 4 weeks (convalescent phase) from 44 HZ patients. All 44 healthy volunteers provided blood and saliva samples once. RESULTS: The median VZV IgA titers in acute-phase (5.2 mIU/mL, P < 0.001) and convalescent-phase (15.8 mIU/mL, P < 0.001) serum samples from HZ patients were significantly higher than those in HCs (1.35 mIU/mL). VZV IgA positivity was detected in about 20% of acute phase serum and convalescent-phase serum of HZ patients. The median VZV IgG antibody titers of HZ patients during acute (1,471.0 mIU/mL, P < 0.001) and convalescent (4,934.7 mIU/mL, P < 0.001) phases were significantly higher than the median titer reported for HCs (591.6 mIU/mL). A four-fold or higher increase in VZV IgG antibody titer was observed in 36.4% of HZ patients. CONCLUSION: VZV IgA positivity or four-fold or higher increase in VZV IgG antibody titers were not detected in a satisfactory proportion of HZ-infected patients. However, the titer of VZV IgA or IgG antibody particularly in convalescent-phase sera may discriminate HZ patients from HCs.

Association between CYP2D6 phenotype and recurrence of Plasmodium vivax infection in south Korean patients.

BACKGROUND: Primaquine is activated by CYP2D6 in the hepatocytes. In Korea, primaquine is the only hypnozoitocidal agent used for patients with vivax malaria. Thus, patients with poor CYP2D6 activity could have an increased risk of primaquine failure and subsequent relapse. The study sought to identify the association between CYP2D6 phenotype and recurrence of malaria in Korean patients. METHODS: A total of 102 patients with vivax malaria were prospectively enrolled from eight institutions in Korea. An additional 38 blood samples from patients with recurred vivax malaria were provided by the Korea Disease Control and Prevention Agency. Malaria recurrence was defined as more than one episode of vivax malaria in the same or consecutive years. CYP2D6 star alleles, phenotypes, and activity scores were examined. RESULTS: Genotyping for CYP2D6 was successful in 101 of the prospectively enrolled patients and 38 samples from the Korea Disease Control and Prevention Agency, of which 91 were included in the no-recurrence group and 48 were included in the recurrence group. Reduced CYP2D6 activity (intermediate metabolizer) phenotype was more common in the recurrence group than in the no-recurrence group (OR, 2.33 (95% CI, 1.14-4.77); p = 0.02). Patients with lower CYP2D6 activity had a higher probability of recurrence (p = 0.029). CONCLUSION: This study suggests that CYP2D6 polymorphism may affect primaquine efficacy and thus Plasmodium vivax recurrence in Korea.

Four Times of Relapse of Plasmodium vivax Malaria Despite Primaquine Treatment in a Patient with Impaired Cytochrome P450 2D6 Function.

Plasmodium vivax exhibits dormant liver-stage parasites, called hypnozoites, which can cause relapse of malaria. The only drug currently used for eliminating hypnozoites is primaquine. The antimalarial properties of primaquine are dependent on the production of oxidized metabolites by the cytochrome P450 isoenzyme 2D6 (CYP2D6). Reduced primaquine metabolism may be related to P. vivax relapses. We describe a case of 4 episodes of recurrence of vivax malaria in a patient with decreased CYP2D6 function. The patient was 52-year-old male with body weight of 52 kg. He received total gastrectomy and splenectomy 7 months before the first episode and was under chemotherapy for the gastric cancer. The first episode occurred in March 2019 and each episode had intervals of 34, 41, and 97 days, respectively. At the first and second episodes, primaquine was administered as 15 mg for 14 days. The primaquine dose was increased with 30 mg for 14 days at the third and fourth episodes. Seven gene sequences of P. vivax were analyzed and revealed totally identical for all the 4 samples. The CYP2D6 genotype was analyzed and intermediate metabolizer phenotype with decreased function was identified.

Development of a Cranial Suture Traction Therapy Program for Facial Asymmetry Correction Using the New Delphi Technique.

Background and Objectives: We aimed to develop a cranial suture traction therapy program, a non-surgical therapeutic method for facial asymmetry correction. Materials and Methods: Six experts, including rehabilitation medicine specialists, oriental medical doctors, dentistry specialists, five experts, including Master's or doctoral degree holders in skin care and cosmetology with more than 10 years of experience in the field, 4 experts including educators in the field of skin care, a total of 15 people participated in the validation of the development of the cranial suture traction therapy program in stages 1 to 3. Open questions were used in the primary survey. In the second survey, the results of the first survey were summarized and the degree of agreement regarding the questions in each category was presented. In the third survey, the degree of agreement for each item in the questionnaire was analyzed statistically. Results: Most of the questions attained a certain level of consensus by the experts (average of ≥ 4.0). The difference between the mean values was the highest for the third survey at 0.33 and was the lowest between the second and third surveys at 0.47. The results regarding the perceived degree of importance for each point of the evaluation in both the second and third stages of the cranial suture traction therapy program were verified using the content validity ratio. The ratio for the 13 evaluation points was within the range of 0.40-1.00; thus, the Delphi program for cranial suture traction therapy verified that the content was valid. Conclusions: As most questions attained a certain level of consensus by the experts, it can be concluded that these questions are suitable, relevant, and important. The commercialization of the cranial suture traction treatment program will contribute to the correction and prevention of facial dislocations or asymmetry, and the developed treatment will be referred to as cranial suture traction therapy (CSTT).

Adult-onset Still's Disease after BNT162b2 mRNA COVID-19 Vaccine.

The coronavirus disease 2019 (COVID-19) pandemic is being overcome by widespread inoculation with various COVID-19 vaccines, but concerns about the safety of the vaccines are a major hurdle to widespread vaccination. We report the first case of adult-onset Still's disease (AOSD) developing in a 36-year-old, previously healthy woman after the first dose of BNT162b2 mRNA COVID-19 vaccine (Pfizer). She visited our hospital due to high spiking fever and sore throat that developed 10 days after vaccination. Based on thorough investigations and changes in symptoms and signs after admission, she was diagnosed with AOSD and treated with high dose steroids and tocilizumab. This report suggests the possibility that AOSD could be triggered by COVID-19 vaccines through activation of the innate immune system.

Increasing Malaria Parasite Clearance Time after Chloroquine Therapy, South Korea, 2000-2016.

We reviewed the clinical efficacy of chloroquine for Plasmodium vivax malaria, the changing trend of parasite clearance time, and fever clearance time during 2000-2016 in South Korea. Median parasite clearance time and fever clearance time increased significantly over the study period. Chloroquine was mostly underdosed when used to treat P. vivax malaria.

Comparative Analysis of Root Canal Filling Debris and Smear Layer Removal Efficacy Using Various Root Canal Activation Systems during Endodontic Retreatment.

The complete removal of obturation material can be a challenge in nonsurgical root canal retreatment. The insufficient removal of obturation material is a reason for root canal retreatment failure. The purpose of this study was to assess the efficacy of different final root canal irrigation activation methods in removing debris and smear layers in the apical and middle portions of root canals during retreatment. Sixty-six distal roots of freshly extracted molars were randomly divided into six groups: (1) primary root canal treatment with no obturation (negative control); (2) retreatment with only conventional instrumentation and irrigation (positive control); (3) retreatment with additional ultrasonic irrigation using the Piezon Master 700; (4) ultrasonic irrigation with the ENDOSONIC Blue; (5) sonic irrigation with the EDDY; and (6) multisonic irrigation with the GentleWave system. Roots were split and prepared for scanning electron microscopic (SEM) evaluation. Acquired images were assessed to quantify the amount of debris and smear remaining. Among the treatment groups, Group 6 had a significantly lower debris score than Group 2 (positive control) in both the middle and apical regions (p = 0.004, p = 0.012). All treatment groups showed significantly lower smear scores than Group 2 in the middle and apical regions (p < 0.05). The GentleWave multisonic System showed a more optimal cleaning efficacy of the root canal debris but did not differ significantly with the tested passive ultrasonic or sonic irrigation method.

Relationships of varicella zoster virus (VZV)-specific cell-mediated immunity and persistence of VZV DNA in saliva and the development of postherpetic neuralgia in patients with herpes zoster.

There are no surrogate markers for the development of postherpetic neuralgia (PHN) in patients with herpes zoster (HZ). All patients with HZ were prospectively enrolled to evaluate the associations of saliva varicella zoster virus (VZV) DNA persistence and VZV-specific cell-mediated immunity (CMI) with the development of PHN. Slow clearers were defined if salivary VZV DNA persisted after day 15. Salivary VZV was detected in 60 (85.7%) of a total of 70 patients with HZ on initial presentation. Of 38 patients for whom follow-up saliva samples were available, 26 (68.4%) were classified as rapid clearers and 12 (31.6%) as slow cleares. Initial VZV-specific CMI was lower in slow clearers than rapid clearers (median 45 vs 158 spot forming cells/10 6 cells, P = .02). Of the 70 patients with HZ, 22 (31.4%) eventually developed PHN. Multivariate analysis showed that slow clearers (OR, 15.7, P = .01) and lower initial VZV-specific CMI (OR, 13.8, P = .04) were independent predictors of the development of PHN, after adjustment for age and immunocompromised status. Initial low VZV CMI response and persistence of VZV DNA in saliva may be associated with the development of PHN.

Impact of health care-associated community-onset cellulitis in Korea: a multicenter study.

We conducted a multicenter study to determine the clinical and microbiological characteristics of health care-associated (HCA) cellulitis in Korea. We retrospectively reviewed the medical records of patients who had been diagnosed with community-onset cellulitis. Of the 2208 cellulitis patients, 232 (10.5%) had HCA cellulitis, 1243 (56.3%) patients were hospitalized, and 15 (0.7%) died in hospital. Compared with community-acquired (CA) cellulitis, patients with HCA cellulitis were older and more frequently presented with comorbidity and septic shock. A total of 355 microorganisms were isolated from 314 patients (14.2%). Staphylococcus aureus (134 isolates) was the most common organism, followed by Streptococcus spp. (86 isolates) and Gram-negative fermenters (58 isolates). Methicillin-resistant S. aureus (MRSA) accounted for 29.1% (39/134) of S. aureus infections. None of the Gram-negative fermenters were resistant to carbapenem. The antibiotic susceptibility pattern of isolated microorganisms was not different between HCA and CA cellulitis. In patients with HCA cellulitis, S. aureus (11.2% [26/232] vs. 5.5% [108/1976], p = 0.001), including MRSA (4.3% [10/232] vs. 1.5% [29/1976], p = 0.003) and Gram-negative fermenters (6.0% [14/232] vs. 2.3% [44/1976], p = 0.002), were more common causative organisms than in CA-cellulitis patients. Age ≥ 65 years, septic shock, and HCA infection were statistically significant factors associated with in-hospital mortality.

Early Intravenous Colistin Therapy as a Favorable Prognostic Factor for 28-day Mortality in Patients with CRAB Bacteremia: a Multicenter Propensity Score-Matching Analysis.

BACKGROUND: Carbapenem-resistant Acinetobacter baumannii (CRAB) infection is associated with high mortality. One of the strategies to reduce the mortality in patients with CRAB infections is to use intravenous colistin early but the effect of this strategy has not been proven. Therefore, we investigated the association of early colistin therapy with 28-day mortality in patients with CRAB bacteremia. METHODS: This retrospective multicenter propensity score-matching analysis was conducted in the Korea by reviewing the medical records of adult patients with CRAB bacteremia between January 2012 and March 2015. Early colistin therapy was defined as intravenous colistin administration for > 48 hours within five days after the blood culture collection. To identify the risk factors associated with the 28-day mortality in CRAB bacteremia, the clinical variables of the surviving patients were compared to those of the deceased patients. RESULTS: Of 303 enrolled patients, seventy-six (25.1%) patients received early colistin therapy. The 28-day mortality was 61.4% (186/303). Fatal or rapidly-fatal McCabe classifications, intensive care unit admission, Sequential Organ Failure Assessment scores ≥ 8, vasopressor use, and acute kidney injury were statistically independent poor prognostic factors. Catheter-related infection and early colistin therapy (adjusted odds ratio [aOR], 0.45; 95% confidence interval [CI], 0.21-0.94) were independent favorable prognostic factors associated with 28-day mortality in patients with CRAB bacteremia. Early colistin therapy was still significantly associated with lower 28-day mortality in the propensity score-matching analysis (aOR, 0.31; 95% CI, 0.11-0.88). CONCLUSION: This study suggests that early colistin therapy might help reduce the mortality of patients with CRAB bacteremia.

Diagnostic Usefulness of Varicella-Zoster Virus Real-Time Polymerase Chain Reaction Analysis of DNA in Saliva and Plasma Specimens From Patients With Herpes Zoster.

Background: We evaluated the diagnostic usefulness of polymerase chain reaction (PCR) analysis for detecting varicella-zoster virus (VZV) infection and reactivation of VZV, using DNA extracted from saliva and plasma specimens obtained from subjects with suspected herpes zoster and from healthy volunteers during stressful and nonstressful conditions. Methods: There were 52 patients with a diagnosis of herpes zoster (group 1), 30 with a diagnosis of zoster-mimicking disease (group 2), and 27 healthy volunteers (group 3). Saliva and plasma samples were evaluated for VZV DNA by real-time PCR analysis. Results: Among patients with suspected herpes zoster (ie, patients in groups 1 and 2), the sensitivity of PCR analysis of salivary DNA for detecting VZV (88%; 95% confidence interval [CI], 74%-95%) was significantly higher than that of PCR analysis of plasma DNA (28%; 95% CI, 16%-44%; P < .001), whereas the specificity of PCR analysis of salivary DNA (100%; 95% CI, 88%-100%) was similar to that of PCR analysis of plasma DNA (100%; 95% CI, 78%-100%; P > .99). VZV DNA was not detected in saliva and plasma samples from group 3 (0%; 95% CI, 0%-14%). Conclusions: Real-time PCR analysis of salivary DNA is more sensitive than that of plasma DNA for detecting VZV among patients with suspected herpes zoster. We found no subclinical reactivation of VZV in group 3 following exposure to common stressful conditions.

Impact of Vancomycin MIC on Treatment Outcomes in Invasive Staphylococcus aureus Infections.

There are conflicting data on the association of vancomycin MIC (VAN-MIC) with treatment outcomes in Staphylococcus aureus infections. We investigated the relationship between high VAN-MIC and 30-day mortality and identified the risk factors for mortality in a large cohort of patients with invasive S. aureus (ISA) infections, defined as the isolation of S. aureus from a normally sterile site. Over a 2-year period, 1,027 adult patients with ISA infections were enrolled in 10 hospitals, including 673 (66%) patients with methicillin-resistant S. aureus (MRSA) infections. There were 200 (19.5%) isolates with high VAN-MIC (≥1.5 mg/liter) by Etest and 87 (8.5%) by broth microdilution (BMD). The all-cause 30-day mortality rate was 27.4%. High VAN-MIC by either method was not associated with all-cause 30-day mortality, and this finding was consistent across MIC methodologies and methicillin susceptibilities. We conclude that high VAN-MIC is not associated with increased risk of all-cause 30-day mortality in ISA infections. Our data support the view that VAN-MIC alone is not sufficient evidence to change current clinical practice.

Optimal Duration of Antibiotic Therapy in Patients With Hematogenous Vertebral Osteomyelitis at Low Risk and High Risk of Recurrence.

BACKGROUND: The optimal duration of antibiotic treatment for hematogenous vertebral osteomyelitis (HVO) should be based on the patient's risk of recurrence, but it is not well established. METHODS: A retrospective review was conducted to evaluate the optimal duration of antibiotic treatment in patients with HVO at low and high risk of recurrence. Patients with at least 1 independent baseline risk factor for recurrence, determined by multivariable analysis, were considered as high risk and those with no risk factor as low risk. RESULTS: A total of 314 patients with microbiologically diagnosed HVO were evaluable for recurrence. In multivariable analysis, methicillin-resistant Staphylococcus aureus infection (adjusted odds ratio [aOR], 2.61; 95% confidence interval [CI], 1.16-5.87), undrained paravertebral/psoas abscesses (aOR, 4.09; 95% CI, 1.82-9.19), and end-stage renal disease (aOR, 6.58; 95% CI, 1.63-26.54) were independent baseline risk factors for recurrence. Therefore, 191 (60.8%) patients were classified as low risk and 123 (39.2%) as high risk. Among high-risk patients, there was a significant decreasing trend for recurrence according to total duration of antibiotic therapy: 34.8% (4-6 weeks [28-41 days]), 29.6% (6-8 weeks [42-55 days]), and 9.6% (≥8 weeks [≥56 days]) (P = .002). For low-risk patients, this association was still significant but the recurrence rates were much lower: 12.0% (4-6 weeks), 6.3% (6-8 weeks), and 2.2% (≥8 weeks) (P = .02). CONCLUSIONS: Antibiotic therapy of prolonged duration (≥8 weeks) should be given to patients with HVO at high risk of recurrence. For low-risk patients, a shorter duration (6-8 weeks) of pathogen-directed antibiotic therapy may be sufficient.

Health care-associated acute pyelonephritis is associated with inappropriate empiric antibiotic therapy in the ED.

BACKGROUND: Acute pyelonephritis (APN) is one of the most common bacterial infections. Because health care-associated (HCA) infections in the community setting have similar characteristics to hospital-acquired infections, HCA infections should be distinguished from community-acquired (CA) infections. However, the impact of HCA-APN on treatment outcomes has not been clearly defined. This study aimed to analyze the impact of HCA-APN on the appropriateness of empiric antibiotic therapy and outcomes in community-onset APN. METHODS: We prospectively identified women older than 18years who were hospitalized with APN via the emergency department and whose urine culture grew bacteria at 10 acute care hospitals in South Korea. RESULTS: Of the 388 APN episodes that were included, 99 (25.5%) were HCA-APN and 289 (74.5%) were CA-APN. Compared with patients with CA-APN, patients with HCA-APN had comorbid conditions and septic shock more frequently. Health care-associated APN was caused by resistant uropathogens more often. Patients with HCA-APN had poorer outcomes (ie, early/final clinical and microbiologic failures); however, this was not statistically significant. Patients with HCA-APN had significantly longer hospital stays than did patients with CA-APN. In the multivariable logistic regression analysis for inappropriate empiric therapy, HCA-APN (odds ratio, 1.96; 95% confidence interval, 1.07-3.57; P=.03) and being bed-ridden (odds ratio, 3.04; 95% confidence interval, 1.31-7.07; P=.01) were significant. CONCLUSIONS: Health care-associated APN was associated with inappropriate empiric antibiotic therapy, which might lead to worse outcomes. These HCA factors should be considered when prescribing empiric antibiotic therapy in patients with community-onset APN.

Therapeutic outcomes of hematogenous vertebral osteomyelitis with instrumented surgery.

BACKGROUND: Patients with hematogenous vertebral osteomyelitis (HVO) occasionally require instrumentation for spinal stabilization. However, placing instrumentation in the setting of spinal infection raises concerns about recurrent infection due to bacteria adhering to the foreign material. In this study, we evaluated the therapeutic outcomes of patients with HVO who underwent instrumented surgery. METHODS: We conducted a retrospective chart review of adult patients with microbiologically diagnosed HVO who underwent surgical intervention in 5 tertiary care hospitals over an 8-year period. RESULTS: A total of 153 patients with HVO underwent surgical management for their infections. Of these 153 patients, 94 (61.4%) underwent surgical debridement alone (noninstrumented surgery) and 59 (38.6%) underwent surgical debridement and instrumentation (instrumented surgery). The median durations of antibiotic therapy were 66 and 80 days for the noninstrumentation and instrumentation groups, respectively (P = .22). Clinical outcomes were similar between the groups, including rates of infection-related death (2.1% vs 0%; P = .52), primary failure (1.1% vs 5.1%; P = .30), and recurrence (4.8% vs 6.8%; P = .72). Among the instrumentation group, there was a significant decreasing trend for recurrence according to total duration of antibiotic therapy: 22.2% (4-6 weeks), 9.1% (6-8 weeks), and 2.6% (≥ 8 weeks; P = .04). Duration of pre-instrumentation antibiotic therapy and single-stage operation (vs 2-stage operation) were not risk factors for recurrence. CONCLUSIONS: Spinal instrumentation in patients with HVO may be safe with pathogen-directed prolonged antibiotic therapy and should not be abandoned or delayed solely because of the risk of recurrence.

Reactivation of Varicella-Zoster Virus in Patients with Lung Cancer Receiving Immune Checkpoint Inhibitors: Retrospective Nationwide Population-Based Cohort Study from South Korea.

BACKGROUND: This study aimed to determine the association between immune checkpoint inhibitors (ICIs) and the risk of herpes zoster (HZ) incidence in patients with lung cancer. METHOD: We obtained national claims data of 51,021 patients from South Korea with lung cancer between August 2017 and December 2021. The study population was classified into ICI and non-ICI groups based on the prescription of ICIs at least once during the study period. To estimate the effects of ICIs treatment compared with those without ICIs treatment on HZ incidence, we used the Cox proportional hazards model adjusted for sex, age, comorbidities, and concomitant use of immunosuppressive drugs. Stratified analyses based on sex, age, and comorbidities were conducted to identify corresponding risk factors. RESULTS: Of the 51,021 study participants, 897 (1.8%) were prescribed ICIs and 2262 (4.4%) were diagnosed with HZ. Approximately 75.6% of the patients receiving ICIs were male, and the prevalence of diabetes, cardiovascular disease, and chronic lung disease in the ICI group was significantly lower than that in the non-ICIs group. The Kaplan-Meier plot showed that the probability of incidence of HZ in the ICIs group was lower than that in the non-ICIs group. Additionally, treatment with ICIs was associated with a 31% lower incidence of developing HZ when compared to that seen without ICIs treatment (95% confidence interval [CI], 0.48-1.00). This association was stronger in females (hazard ratio [HR], 0.42; 95% CI, 0.19-0.94) and those less than 68 years of age (HR, 0.58; 95% CI, 0.34-0.99). CONCLUSIONS: In these real-world data from an Asian population with lung cancer, ICIs treatment might be associated with a reduced risk of HZ compared to that without ICIs treatment.

Identification and Dynamics of Microsecond Long-Lived Charge Carriers for CsPbBr3 Perovskite Quantum Dots, Featuring Ambient Long-Term Stability.

We analyze the stability and photophysical dynamics of CsPbBr3 perovskite quantum dots (PeQDs), fabricated under mild synthetic conditions and embedded in an amorphous silica (SiOx) matrix (CsPbBr3@SiOx), underscoring their sustained performance in ambient conditions for over 300 days with minimal optical degradation. However, this stability comes at the cost of a reduced photoluminescence efficiency. Time-resolved spectroscopic analyses, including flash-photolysis time-resolved microwave conductivity and time-resolved photoluminescence, show that excitons in CsPbBr3@SiOx films decay within 2.5 ns, while charge carriers recombine over approximately 230 ns. This longevity of the charge carriers is due to photoinduced electron transfer to the SiOx matrix, enabling hole retention. The measured hole mobility in these PeQDs is 0.880 cm2 V-1 s-1, underscoring their potential in optoelectronic applications. This study highlights the role of the silica matrix in enhancing the durability of PeQDs in humid environments and modifying exciton dynamics and photoluminescence, providing valuable insights for developing robust optoelectronic materials.

Thermally Induced Phase Separation of the PEDOT:PSS Layer for Highly Efficient Laminated Polymer Light-Emitting Diodes.

Among various conductive polymers, the poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) film has been studied as a promising material for use as a transparent electrode and a hole-injecting layer in organic optoelectronic devices. Due to the increasing demand for the low-cost fabrication of organic light-emitting diodes (OLEDs), PEDOT:PSS has been employed as the top electrode by using the coating or lamination method. Herein, a facile method is reported for the fabrication of highly efficient polymer light-emitting diodes (PLEDs) based on a laminated transparent electrode (LTE) consisting of successive PEDOT:PSS and silver-nanowire (AgNW) layers. In particular, thermally induced phase separation (TIPS) of the PEDOT:PSS film is found to depend on the annealing temperature (Tanneal) during preparation of the LTE. At Tanneal close to the glass transition temperature of the PSS chains, a PSS-rich phase with a large number of PSS- molecules enhances the work function of the PEDOT:PSS on the glass-side surface relative to the air side. By using the optimized LTEs, bidirectional laminated PLEDs are obtained with a total external quantum efficiency of 2.9% and a turn-on voltage of 2.6 V, giving a comparable performance to that of the reference bottom-emitting PLED based on a costly evaporated metal electrode. In addition, an analysis of the angular characteristics, including the variation in the electroluminescence spectra and the change in luminance according to the emission angle, indicates that the laminated PLED with the LTE provides a more uniform angular distribution regardless of the direction of emission. Detailed optical and electrical analyses are also performed to evaluate the suitability of LTEs for the low-cost fabrication of efficient PLEDs.